Hitting the 8 million mark means not only more people – but more of everything for the bigger Big Apple.

“This should help us in numerous ways,” a beaming Mayor Giuliani said yesterday.

“Most of the formulas that exist with regard to block grants and other formulas in Washington, we’re jumping 10 percent.

“This will help with the money that we need for HRA [Human Resources Administration], the money that we need for ACS [Administration for Children’s Services] and it will assist greatly in law-enforcement programs, some of which are population-based.”

The city receives a myriad of grants from the feds for city programs, including Head Start, currently at $171 million; Childcare and Development at $47 million; $28 million for energy assistance programs; $74 million for day care and meals; $23 million for mass transit; and $129 million in work-force investments.

“All of these are driven by the census numbers,” said Deputy Mayor Rudy Washington.

“Under the housing programs, we would be eligible for more credits, emergency shelter grants, more crime-lab money, more dollars for prosecution, Medicaid, juvenile-justice programs, etc.”

Pointing out that the FBI evaluates crime in per capita rates, officials also boasted that the city continues to lead the nation in crime reduction even with more people than had been factored into the figures.

Ten years ago, the city head count was 7,322,564. For 2000, it jumped to 8,008,278.

Officials credited the coordination of all city agencies in assisting with the count in resulting in what they called less of an undercount than before.

City Planning Commissioner Joe Rose said one winning strategy was to cross-check old census lists with those of housing developments, utility companies, Bell Atlantic, and buildings-department data on rehabilitated buildings and illegal conversions.

About 420,000 new households were discovered.

“We then went out to [the] field and checked. Ultimately, [the Census Bureau] accepted 370,000 of those addresses,” Rose said. “This is the data of history.”

Washington said the new figures also include correctional facilities and people without fixed residences.

“We went under bridges and highways, and we found our homeless population, so we counted just about every New Yorker that we could identify,” he said.

That won’t put a strain on the city’s city social services, he said, because they’ve already been serving more clients than the federal government recognized.

“This is not a burden that just hit New York. The burden has always been here,” Washington said.